A simple estimator for a shared frailty regression model

Summary. We propose a simple estimation procedure for a proportional hazards frailty regression model for clustered survival data in which the dependence is generated by a positive stable distribution. Inferences for the frailty parameter can be obtained by using output from Cox regression analyses. The computational burden is substantially less than that of the other approaches to estimation. The large sample behaviour of the estimator is studied and simulations show that the approximations are appropriate for use with realistic sample sizes. The methods are motivated by studies of familial associations in the natural history of diseases. Their practical utility is illustrated with sib pair data from Beaver Dam, Wisconsin.     

Predictive Bayesian Microbial Dose-Response Assessment Based on Suggested Self-Organization in Primary Illness Response: Cryptosporidium parvum

The probability of illness caused by very low doses of pathogens cannot generally be tested due to the numbers of subjects that would be needed, though such assessments of illness dose response are needed to evaluate drinking water standards. A predictive Bayesian dose-response assessment method was proposed previously to assess the unconditional probability of illness from available information and avoid the inconsistencies of confidence-based approaches. However, the method uses knowledge of the conditional dose-response form, and this form is not well established for the illness endpoint. A conditional parametric dose-response function for gastroenteric illness is proposed here based on simple numerical models of self-organized host-pathogen systems and probabilistic arguments. In the models, illnesses terminate when the host evolves by processes of natural selection to a self-organized critical value of wellness. A generalized beta-Poisson illness dose-response form emerges for the population as a whole. Use of this form is demonstrated in a predictive Bayesian dose-response assessment for cryptosporidiosis. Results suggest that a maximum allowable dose of 5.0 x 10(-7) oocysts/exposure (e.g., 2.5 x 10(-7) oocysts/L water) would correspond with the original goals of the U.S. Environmental Protection Agency Surface Water Treatment Rule, considering only primary illnesses resulting from Poisson-distributed pathogen counts. This estimate should be revised to account for non-Poisson distributions of Cryptosporidium parvum in drinking water and total response, considering secondary illness propagation in the population.     

African Americans and municipal employment: A test of two perspectives

A survey of the extant literature addressing the factors that drive African American municipal employment offers two broad types of explanations: (1) Black political power and (2) institutional. A comparative assessment of the performance of each of these explanations fills a gap in the literature by illuminating the differences of these distinct perspectives when it comes to employment of Blacks in the public sector. Focusing on six Florida cities from 1960 to 2000, this study tests the predictive power of each of these explanations comparatively for four city departments. The findings indicate that the Black political power explanation performs better than the institutional explanation as a predictor of Black employment.     

Construction and selection of quick switching double-sampling system: sample size tightening

A new sampling inspection system involving normal and tightened plans is presented. Performance measures are developed. The average sample number of the newly developed system is compared with those of existing plans. Procedures are indicated an tables are constructed for designing the system indexed by various combinations of parameters.     

Detecting parameter shift in garch models

This paper applies recent theories of testing for parameter constancy to the conditional variance in a GARCH model. The supremum Lagrange multiplier test for conditional Gaussian GARCH models and its robustified variants are discussed. The asymptotic null distribution of the test statistics are derived from the weak convergence of the scores, and the critical values from the hitting probability of squared Bessel process.

Monte Carlo studies on the finite sample size and power performance of the supremum LM tests are conducted. Applications of these tests to S&P 500 indicate that the hypothesis of stable conditional variance parameters can be rejected.     

A case of suspected child abuse by an adolescent mother: The use of short-term psychotherapy

The incidence of pregnancy during adolescence has escalated dramatically in recent years, with an estimated half a million infants born to teenagers each year in the United States. A disproportionately high amount of child abuse and/or neglect is encountered among adolescent parents, underscoring the need for an effective intervention strategy. Short-term psychotherapy may be beneficial in these cases for forging a therapeutic alliance expeditiously and rigorously challenging the patient's resistance. The case described involves alleged abuse by a 16-year-old mother. An intervention was designed to clarify the allegations surrounding the abusive incident, help the mother confront episodes of loss in her own life and overcome feelings of hopelessness engendered by separation from her infant.     

Poverty and social trends in Russia

The article describes the socioeconomic situation of the Russian population and its dynamics in 1992. The analysis is based on series of regional sociological surveys led by the All-Russian Living Standards Research Center and on official Russian statistical data. The basic unit of analysis is the family, and hence family typology approbated both in research and in practical social work is introduced. Besides describing and discussing the growing poverty tendencies in contemporary Russia, the article also contains methodological recommendations for social policy bodies and social workers on the strategy of work in social maintenance and social support of the least secure population strata.     

Significance of the Dermal Route of Exposure to Risk Assessment

The skin is a route of exposure that needs to be considered when conducting a risk assessment. It is necessary to identify the potential for dermal penetration by a chemical as well as to determine the overall importance of the dermal route of exposure as compared with inhalation or oral routes of exposure. The physical state of the chemical, vapor or liquid, the concentration, neat or dilute, and the vehicle, lipid or aqueous, is also important. Dermal risk is related to the product of the amounts of penetration and toxicity. Toxicity involves local effects on the skin itself and the potential for systemic effects. Dermal penetration is described in large part by the permeability constant. When permeability constants are not known, partition coefficients can be used to estimate a chemical's potential to permeate the skin. With these concepts in mind, a tiered approach is proposed for dermal risk assessment. A key first step is the determination of a skin-to-air or skin-to-medium partition coefficient to estimate a potential for dermal absorption. Building a physiologically-based pharmacokinetic (PBPK) model is another step in the tiered approach and is useful prior to classical in vivo toxicity tests. A PBPK model can be used to determine a permeability constant for a chemical as well as to show the distribution of the chemical systemically. A detailed understanding of species differences in the structure and function of the skin and how they relate to differences in penetration rates is necessary in order to extrapolate animal data from PBPK models to the human. A study is in progress to examine anatomical differences for four species.     

EVALUATING CHANGES IN THE DISTRIBUTION OF CAPITAL WEALTH

A small-scale general equilibrium model in which the distribution of capital wealth is a key parameter is employed to examine the potential economic consequences of greater capital wealth equality. Every performance indicator examined – aggregate income, consumption equality, social welfare in the sum-of-utilities sense, and aggregate saving –is improved by greater capital wealth equality. However, the bottom-line social welfare gain, relative to the present high-inequality situation – even from the maximum achievable level of complete equality in capital wealth distribution – would be numerically rather modest.